Ersatz 5.5 mm Nut Driver

A tiny 1/4 inch hex driver handle appeared from the far reaches of a drawer, sporting a handle better suited for tweaking the 3 mm adjusting nuts on the bottom of the M2’s platform than applying actual torque to real fasteners. Rather than breaking a set of nut drivers, I made a simple brass shim to soak up the difference between the handle’s 6.5 mm ID hex and the 5.5 mm OD of the nuts:

Hex driver shim - installed
Hex driver shim – installed

That’s 15 mil = 0.40 mm shimstock to leave enough clearance for my crude forming technique.

Which technique consisted of making a “mandrel” by lining up a trio of Nyloc nuts on a screw, snipping off a suitable shimstock rectangle, and squashing it into shape with parallel-jaw pliers:

Hex driver shim - forming
Hex driver shim – forming

As you’d expect, the shimstock hex came out larger & uglier than the mandrel:

Hex driver shim - formed
Hex driver shim – formed

But that doesn’t matter after it’s tucked inside the driver; it works perfectly.

Took less time to do than to write up …

Micro-Mark Mini Bandsaw

Unlike their craptastic Mini Miter/Cut-off saw, the Micro-Mark Variable Speed Mini Bandsaw seems like a solid improvement over the corresponding Harbor Freight offering:

Micro-Mark Bandsaw - mostly ready
Micro-Mark Bandsaw – mostly ready

That’s the tank for the water-cooling option atop the housing, with the collection tray underneath. It’s screwed to a big wood plank; I’ll probably bench-mount the thing, but that’s stable enough for now.

The right-rear mounting screw hides below the dust collection vacuum port:

Micro-Mark Bandsaw - vacuum fitting
Micro-Mark Bandsaw – vacuum fitting

You must remove the metal fitting that’s screwed to the frame in the obvious manner:

Micro-Mark Bandsaw - right rear screw - installed
Micro-Mark Bandsaw – right rear screw – installed

The slowest speed runs a bit faster than I’d like, but I admit to being a sissy.

The 14 tpi blade cuts wood just fine:

Micro-Mark Bandsaw - first cut
Micro-Mark Bandsaw – first cut

The 24 tpi blades should chop up the smaller chunks I generally work with around here.

Bonus: the blade guide just barely clears my huge block of machinable wax.


Micro-Mark Mini Miter / Cut-off Saw

I bought a 2 inch Micro-Mark Mini Miter / Cut-off Saw to cut screws & brass tubing, in the hopes that it would be somewhat better than the essentially equivalent Harbor Freight offering. I think that’s true, but it’s a near thing.

Apparently, the saws all come from the same factory with the same bass-ackwards vise:

Micro-Mark Cutoff Saw - vise side view
Micro-Mark Cutoff Saw – vise side view

The V-groove should be on the fixed jaw, where it would more-or-less precisely align rods / cylinders with the blade. The moveable jaw isn’t dovetailed to the base of the vise, so it ends up wherever it stops and, somehow, they managed to machine the end of the screw shaft off-center from the shaft, so the moveable jaw moves in a small circle as you tighten it.

A small punch mark locks the jaw to the screw; you can pull the disk on the shaft past the indentation by turning the knob with sufficient enthusiasm:

Micro-Mark Cutoff Saw - clamp jaw detail
Micro-Mark Cutoff Saw – clamp jaw detail

The hole in the vise, just under the disk, lets somebody whack the jaw with a punch.

Some machining or an entirely new vise setup lies in the future of this thing.

I mounted it on a scrap of countertop by transfer-punching the base holes, only to discover that the punch didn’t leave a mark for one hole, even though a dent was clearly visible at the bottom of the hole with the saw on the countertop.

A bit of headscratching later:

Micro-Mark Cutoff Saw - unfinished casting hole
Micro-Mark Cutoff Saw – unfinished casting hole

Apparently the core for that hole in the injection mold didn’t seat quite right. The layer was thin enough to drill out easily.

The blade is identical with the Harbor Freight blades I’m using on the Sherline, right down to the printed legend declaring it fits saws with non-Micro-Mark part numbers:

2 inch blades - Micro-Mark vs Harbor Freight
2 inch blades – Micro-Mark vs Harbor Freight

Granted, the Micro-Mark blade on the left has nicer printing, but MM blades run $15 each and HF offers a three-pack for ten bucks. Note the carefully positioned thumb in the Micro-Mark picture.

Beware of cheap imitations!” says Micro-Mark.

Tempting TV Channel

One of the motel’s TV channels offered this diversion:

Fedora console on motel TV
Fedora console on motel TV

Alas, no combination of keys on the overly complex remote fed themselves to tty1. That didn’t surprise me, but ya gotta try, y’know.

Contrary to what you might think, that’s a well-focused image. Apparently, someone, somewhere, aimed a crappy camera at a monitor and devoted one video input to the result.

I wonder what critical infrastructure runs a Linux distro that end-of-lifed in December 2009.

We’ll never know the rest of the story…

Carnival Bears on Interstate 87!

Returning from Rochester & Points North, I spotted something in the rearview mirror that could have been either a Yellow Submarine or a storage tank. As whatever it was got closer, the view got weirder:

Bears on I-87 - approaching
Bears on I-87 – approaching

Huh. Who’d’a thunk it?

Bears on I-87 - passing
Bears on I-87 – passing

A stiff crosswind pushed them all over the lane:

Bears on I-87
Bears on I-87

I hope they arrived at their destination with the shiny side up and the rubber side down.

Mary clicked the camera for these.

Craftsman Mower Flywheel Key: Intact

The mower tried to eat a protruding root, emitted a horrible crash, and ran poorly until I shut it off, after which it refused to restart. Hoping against hope that the flywheel’s aluminum key had sheared, I pulled the cover, removed the starter, and found:

Mower flywheel key
Mower flywheel key

Alas, the key is in fine shape. I made the two diagonal scratches to confirm it really is aluminum.

After letting the mower sit for a day, it started and ran briefly, blatted a giant backfire that probably startled the neighborhood (because I had the exhaust aimed into the garage, which served as a wonderful resonator), died a sudden death, then made clanking sounds whenever I pulled the rope. Something is definitely broken inside, but I suspect diagnosing & fixing it will require more time and money than is justified.

I no longer form deep emotional attachments to lawn mowers, so I ordered a similar one online and the local Sears had it ready for pickup in an hour.

If I had to pull the flywheel, I’d tap the two obvious holes (one behind the shaft in the picture) and gimmick up a puller with two matching screws around a central bolt that does the heavy lifting; I can’t justify the Special Service Tool I’m sure it requires.

The old mower lasted an hour at the foot of the driveway with a “FREE – Engine probably severely broken” sign affixed to its handle; both parties got a great deal on that transaction!

APRS/GPS + Voice Interface: Improved PTT Button Cap

Long ago, Mary picked out a PTT switch with a raised, square post that provided a distinct shape and positive tactile feedback:

PTT Button - bare post
PTT Button – bare post

Time passes, she dinged her thumb in the garden, and asked for a more rounded button. I have some switches with rounded caps, but replacing the existing switch looked a lot like work, sooooo:

PTT Button Cap - Slic3r preview
PTT Button Cap – Slic3r preview

As with all small objects, building them four at a time gives the plastic in each one time to cool before slapping the next layer on top:

PTT Button - on platform
PTT Button – on platform

The hole in the cap is 0.2 mm oversize, which results in a snug press fit on the small ridges barely visible around the post in the first image:

PTT Button - rounded cap
PTT Button – rounded cap

Rather than compute the chord covering the surface, I just resized a sphere to twice the desired dome height (picked as 6 threads, just for convenience) and plunked it atop a cylinder. Remember to expand the sphere diameter by 1/cos(180/sides) to make it match the cylinder and force both to have the same number of sides.

If it falls off, I have three backups.

The OpenSCAD source code as a GitHub Gist:

// PTT Button cap
// Ed Nisley KE4ZNU - June 2016
//- Extrusion parameters - must match reality!
ThreadThick = 0.20;
ThreadWidth = 0.40;
Protrusion = 0.1;
HoleWindage = 0.2;
// Dimensions
Post = [3.8,3.8,3.0];
OD = 0;
Button = [12,0+Post[2],6*ThreadThick];
NumSides = 8*4;
//- Build it
difference() {
union() {
translate([0,0,Post[2]/2 - Protrusion])
cube(Post + [HoleWindage,HoleWindage,Protrusion],center=true);